Abstract

Random perturbations play an important role in the crosstalk of multicore fibers, and can be captured by statistical coupled-mode calculations. In this approach, phase matching contributes a multiplicative factor to the average crosstalk, depending on the perturbation statistics and any intentional heterogeneity of neighboring cores. The impact of perturbations is shown to be qualitatively different depending on whether they are gradually varying, or have short-length (centimeter-scale) variations. This insight implies a novel crosstalk suppression strategy: fast modulation of a bend perturbation by spinning the fiber can disrupt the bend-induced phase matching.

Figures (7)

The standard bend model includes a bend-induced index tilt proportional to the curvature. Bends and other length-varying perturbations shift the index mismatch between cores, and lead to intermittent resonant coupling.

The phase-matching factor of crosstalk is calculated as a power spectral density (solid) and compared to the quasi-static approximation (dashed black) for the simple case where the index perturbation is due to constant bend radius and gradual orientation drift.

For a very fast, well-controlled spin (1turn/cm) spin periodicity leaves large gaps in the power spectral density: Crosstalk in this calculation is dramatically reduced for cores with index mismatch in between 0 and 1.55 × 10−4 .

While fast spin can disrupt bend-mediated phase matching between cores, other perturbations may not share the spin periodicity. Low-crosstalk regimes remain as long as non-bend perturbations are not too large.